immature 

A word utilized to describe someone who exibits the behavioral patterns of a child. Such people tend to be impulsive; an example of which, is a tendency to use unwanted physical contact on another person, or making statements in complete ignorace and crudeness. Immature people also tend to make narrow associations of certain actions with certain effects, such as the association of biking with falling off.

immature by Anonymous October 21, 2003

immature 

One who abuses drugs to feel grown up.
One who abuses alcohol to feel grown up.
One who calls people immature.

The majority of the teenage population.(immature)

immature by a-nonny-moosee February 20, 2009

immature 

someone who looks for all the dirty words in a dictionary first.

esp. young, immature, curious people (or old perverts)

immature by Zoeslut January 18, 2009

immature 

A childish person.

"Don't be so immature"

immature by grayjoycon February 10, 2018

immature 

1.) 99% of high school chicks who laugh hysterically at things that are not remotely funny 2.) 90% of college chicks who soak themselves up with drama and send 4 different text messages to their boyfriends, all of which say the same thing

Amy just laughed hysterically cuz she accidentally ran over her crushes mailbox, that is so immature.

immature by krh90 September 27, 2009

immature 

I agree with this definition:

98% of the people on Urban Dictionary

"i looked up the definition of wank! ha ha ha!"

ha ha very (not) funny

immature by peedoff December 14, 2004

immature 

Term used to describe all the teenagers, "frat boy types", posers, thugs, and other assorted obnoxious entities who post all the inane, stupid, sexually graphic definitions for actual and made-up words on Urban Dictionary.

Most of you immature little fucktards will never attend college or achieve anything worthwhile in life, on account of your ability to reason and communicate like 12 year olds.

immature by Anonymous Hater of Stupidity July 20, 2008